A square baler may be driven along a crop windrow to pick up crop material and feed the crop material into a stuffer chute to form a charge for subsequent delivery to a baling chamber where it is compacted by a reciprocating plunger. The characteristics of the charge in the stuffer chute can affect the characteristics of a resulting bale. For example, unenven loading where one side of the charge in the stuffer chute has a greater volume of crop material than another can have an adverse effect on the shape of the resulting bale. Overloading the stuffer chute can result in high stress levels, the shearing of shear bolts of the stuffer drive and other problems. Underloading the stuffer chute leads to poor density and capacity.
Generally, when a continuously reciprocating plunger is employed by a baler the mechanics are such that a window for triggering the stuffing of the charge from the stuffer chute into the baling chamber opens and closes as the plunger moves across an outlet of the stuffer chute and the drive of the stuffer fork rotates through a cycle. Thus, if a charge is not swept from the stuffer chute into the baling chamber during a first open window then additional crop material is added to the charge while awaiting the next open window so that the charge grows in size while awaiting the next open window.
In an attempt to control the triggering of the stuffer, the prior art has employed mechanical trip devices, that employ an either-or trigger, such as a spring-loaded pressure switch, that trips the stuffer whenever a minimum pressure level within the stuffer chamber is reached. While this arrangement is suitable for its intended purpose, it has several drawbacks. For example, if the specific pressure required by the spring trigger is not reached during a first open window then the charge may grow to an undesirably large size by the time the second window opens, so that the stuffer attempts to sweep the larger charge into the baling chamber which can lead to the aforementioned problems. Thus, in some cases it may be more desirable to sweep a small charge that is below a minimum pressure setting than to attempt to sweep a larger charge later.
The prior art devices also do not provide a way to quickly detect problems with a charge in a stuffer chute. Thus, one must often wait until after the charge has been swept into the baling chamber and the bale is formed to discover such problems, which may prove too late to take corrective action with respect to that particular bale. For example, an operator of such prior art devices is provided with little or no information about characteristics of the charge in the stuffer chute thereby making it difficult to identify problems. An operator will likely have to wait until a bale of undesirable quality is formed, or until the shear bolts are sheared to determine that there is a problem with the wrappers of the stuffer chute or that the setting of the spring tension is wrong or driving at improper speed. Furthermore, the prior art arrangements do not provide sufficient information to allow an operator to take an appropriate corrective driving actions, such as changing the approach to a windrow in an effort to improve the charge characteristics. Furthermore, even when adjustments are made to the stuffer it is often difficult for an operator to quickly determine the effect of such adjustments on the charge as the operator is provided little information about the charge during charge formation in the stuffer chute.
In addition, characteristics of the bale in the baling chamber are typically not used in preparing the charge thereby leading to charges that may be undesirable for a particular bale being formed in the baling chamber. For example, when the formation of the bale in the baling chamber is nearly complete, it may be desirable to provide a charge of smaller than normal size to finish the bale to an accurate desired length.